Test-Time Alignment of Text-to-Image Diffusion Models via Null-Text Embedding Optimisation
Researchers propose Null-Text Test-Time Alignment (Null-TTA), a novel method for adapting text-to-image diffusion models during inference by optimizing the unconditional embedding in classifier-free guidance rather than manipulating latent variables. This approach maintains semantic coherence while achieving superior alignment to target rewards without reward hacking, establishing a new paradigm for test-time model adaptation.